An electrical air conditioning system for a vehicle is provided in a related art. The system is a battery-powered single electric compressor air conditioning system. In the system, a mechanical compressor is replaced by an electric compressor, and a power battery is provided to supply power to the electric compressor, so that the refrigerant flowing from an evaporation chamber is compressed to be the working fluid having a high temperature and a high pressure, and then the working fluid is fed to a condenser to cool, and the later working theory is the same with that of the conventional air conditioning system.
However, when the vehicle is parking for a long time or in a traffic jam condition, this kind of air conditioning system may cause an insufficient voltage problem of the battery, which may cause the vehicle cannot start properly.